Patent document D1 describes an invention relating to a container, the so-called the “delaminable bottle,” which is molded by a direct blow molding process, and in which an inner layer that forms a free-to-deflate inner bag is laminated in a peelable manner with an inner surface of an outer layer that forms an outer shell. The delaminable bottle of this kind is in use as a discharge container of a squeeze type combined with a cap having a check valve installed or as a discharge container combined with a manual pump.
FIG. 12 is a side view showing a typical example of the discharge container of the squeeze type using a delaminable bottle as the container main-body. FIG. 13 is cross-sectional view taken along line G-G in FIG. 12, This discharge container is a delaminable bottle obtained by the direct blow molding process (a process for using an extruded cylindrical parison and blow molding the parison into a bottle in a mold). A cap 109 having two check valves 109Va, 109Vb is screwed on a neck 102 of a container main-body 101. The container main-body 101 has a laminar structure in which an inner layer 112 for forming an inner bag 107 that can be deflated with the decrease in volume of a content fluid is laminated in a peelable manner with an outer layer 111 that forms an outer shell 106. An air intake vent 119 is open in a portion of the outer shell 106 of the neck 102 to take in outside air.
In the case of the discharge container utilizing such a delaminable bottle as described above, there is a pressure drop inside the inner bag 107 after the content fluid L has been discharged. At that time the inner layer 112 peels from the outer layer 111, thus allowing the inner bag 107 to be deflated with the decrease in the volume of the content fluid. Under this condition, the check valve 109Va works to prevent outside air from entering the inside of the inner bag 107, while the check valve 109Vb also works in cooperation. Because of the actions and effects of these two valves, the quality of the content fluid L is effectively protected against deterioration. Outside air is taken into a space between the outer layer 111 and the inner layer 112 in a volume as much as the volume of the content fluid that has been discharged. After a portion of the content fluid has been discharged, the outer shell 106 can be restored to its original shape. Thus, the discharge container has high performance in the aspects of usability and outer appearance.
As often observed in the discharge containers of this type, when the inner bag 107 deforms with the decrease in the volume of the content fluid L, the inner layer 112 on one side comes in close contact with the counterpart on the other side. In that case, flow channels F may get narrow on the way, or even get clogged completely to a point where the ability of the container to discharge the content fluid L is damaged. Still another problem is that it may become impossible to utilize the content fluid L to the last drop. In this respect, the patent document D1 describes a pair of adhered zones 113a where the outer layer 111 is adhered to the inner layer 112 through the intermediary of these adhesive layers 113, which are disposed at symmetrical positions on the central axis of the container main-body 101. As shown in FIG. 13 by two-dot chain lines 112a, 112b, the inner layer 112 that forms the inner bag 107 is controlled to have a certain configuration when the inner bag 107 deforms. In this way, the flow channels F are secured until the content fluid L is cleared off.
The delaminable bottle obtained by the direct blow molding, such as described above, has a bottom seal 108 formed when the parison is pinched off (see FIG. 12). This bottom 108 has a laminar structure comprising an outer layer 111, an inner layer 112, and an outer layer 111, as viewed in vertical section. Although the outer layer 111 in itself is in a steady state, and surrounds the inner layer 112 in tight contact. But since the outer layer 111 and the inner layer 112 are originally formed in a peelable state, this bottom seal 108 can be used as an air intake vent by partially separating between the outer layer 111 and the inner layer 112. On the other hand, there arises an intrinsic problem that a crack tends to open, starting from this bottom seal 108.
In the meantime, the patent document D2 describes an invention of a bottle container to be used as a delaminable bottle, which is obtained by biaxially stretching and blow molding a preform in a shape of a test tube, wherein an outer container and an inner container both made of synthetic resins are put together by an insert molding process to give the bottle a double wall. Such a delaminable bottle of the biaxially stretched, blow molded container enables at least the outer shell to be molded by using a polyethylene terephthalate (PET) resin, which is known to be difficult to mold by means of the direct blow molding process. The delaminable bottle thus obtained can take advantage of such properties as strength, stiffness, gas barrier property, transparency, and glaze, all of which are demonstrated by this biaxially stretched, blow molded container made of a PET resin, or the so-called PET bottle.
The patent document D3 describes an injection molding device utilizing a multi-nozzle section having cylindrical outer, middle, and inner flow channels disposed concentrically and also having a cylindrical joined flow channel disposed at the ends of these flow channels. This document also shows a laminated preform molded by this device so as to have a laminar structure in which an intermediate layer is laminated with, and embedded in, the substrate layers. FIG. 14 shows an example of the preform to be molded by using this device. The preform 201 has a laminar structure in which an intermediate layer 212 having a high gas barrier property is laminated with, and sandwiched between, two substrate layers 211 made of a PET resin in a height range excluding an upper portion of a neck 201 and an entire bottom 205. When this preform 201 is biaxially stretched and blow molded, the container thus obtained has a higher gas barrier property than has the container made of only the PET resin by the intermediate layer 212.